This invention relates to connector and coupling assemblies for electrical cord or cable and more particularly to an improved electrical cord or cable gripping device for use in combination with such assemblies.
In electrical plug wiring devices or coupling or receptacle assemblies wherein a cord or cable comprised of one or more wire conductors is connected to coupling terminals, it is necessary to secure the cord to the assembly so that external tension on the cord will not transmit stress to the internal wire connections. An early attempt to solve this cord gripping problem comprised the use of curved metal plates connected together and to the coupling housing. Such devices were particularly slow and tedious to assemble. Subsequently, a cord gripping device was developed using finger elements formed integrally with the receptacle housing to grip the cord, as shown in U.S. Pat. No. 3,437,980. One disadvantage with the aforesaid patented device was that the tooling for holding the integral finger elements was extremely complex and hence expensive. Another problem arose in the use of the prior art finger elements from the fact that they were drawn into their gripping position by screws connected to an end cap. Often, the screws were not installed to a uniform depth in the end cap and this caused the finger elements to apply unequal loading on the cord and the end cap to be cocked relative to the coupling body.
It is therefore a general object of the present invention to provide an improved cord gripping device for electrical wire devices, such as couplings, that solves the problems and overcomes the disadvantages of prior art devices.
Another object of the present invention is to provide an improved coupling with non-integral detachable gripping fingers that produce a highly effective gripping force on the cord when installed.
Yet another object of the invention is to provide an improved electrical coupling with detachable fingers for gripping the cord attached thereto when engaged by a rotatable end cap and which cooperates with the end cap to prevent it from rotating backwards after being installed.
Another object of the invention is to provide an electrical coupling with a cord gripping device that can be easily connected to an electrical cable without the need for highly skilled labor or special tools.
Another object of the invention is to provide an improved cord gripping coupling assembly, and one that is particularly well adapted for eased and economy of manufacture.